The National Institute for Health and Clinical Excellence (NICE) has issued full guidance to the NHS in England, Wales, Scotland and Northern Ireland on Mini-incision surgery for total knee replacement.

It replaces the previous guidance on Mini-incision surgery for total knee replacement (NICE interventional procedures guidance 117, September 2004).


The most common indication for a total knee replacement is osteoarthritis of the knee joint. The mini-incision total knee replacement involves an incision 10 to 12 cm long over the knee, compared with the conventional total knee replacement which requires an incision 20 to 30 cm long. The same prostheses are inserted using specially designed instruments.

Coding recommendations

W40.- Total prosthetic replacement of knee joint using cement


W41.- Total prosthetic replacement of knee joint not using cement


W42.- Other total prosthetic replacement of knee joint

The NHS Classifications Service has advised NICE that currently these are the most suitable OPCS-4 codes to describe this procedure. The OPCS-4 classification is designed to categorise procedures for analysis and it is not always possible to identify a procedure uniquely.

Your responsibility

This guidance represents the view of NICE, arrived at after careful consideration of the evidence available. When exercising their judgement, healthcare professionals are expected to take this guidance fully into account, and specifically any special arrangements relating to the introduction of new interventional procedures. The guidance does not override the individual responsibility of healthcare professionals to make decisions appropriate to the circumstances of the individual patient, in consultation with the patient and/or guardian or carer. 

All problems (adverse events) related to a medicine or medical device used for treatment or in a procedure should be reported to the Medicines and Healthcare products Regulatory Agency using the Yellow Card Scheme.

Commissioners and/or providers have a responsibility to implement the guidance, in their local context, in light of their duties to have due regard to the need to eliminate unlawful discrimination, advance equality of opportunity, and foster good relations. Nothing in this guidance should be interpreted in a way that would be inconsistent with compliance with those duties. Providers should ensure that governance structures are in place to review, authorise and monitor the introduction of new devices and procedures.

Commissioners and providers have a responsibility to promote an environmentally sustainable health and care system and should assess and reduce the environmental impact of implementing NICE recommendations wherever possible.

  • National Institute for Health and Care Excellence (NICE)